Method and apparatus for combining a targetless optical measurement function and optical projection of information

ABSTRACT

Systems and methods are provided for targetless optical measurement and optical information projection. A non-contact optical measurement device is provided for determining at least one of position and orientation of a workpiece. A projector is provided for projecting a part definition on the workpiece. Advantageously, beams from the non-contact optical measurement device and the projector pass through common optics.

FIELD OF THE INVENTION

This invention relates generally to metrology and, more specifically, tooptical measurement systems and methods.

BACKGROUND OF THE INVENTION

In manufacturing operations, complicated assemblies and contoured partsare often mated to other complicated assemblies and parts. A variety oftechniques are currently used to locate the assemblies and parts formating.

For example, some assembly techniques use factory aids such as templatesthat are made out of paper, Mylarm, or the like to find referencetargets for accurately placing smaller parts on larger parts. Thesefactory aids are subject to wear and tear and, as a result, are replacedfrom time-to-time. The factory aids must be replaced when engineeringchanges are made. Also, errors may be made by manufacturing personnelwhen using the factory aids. All of these aspects of the factory aidsintroduce additional costs into the manufacturing operation.

In other assembly techniques, a laser tracker measures coordinates of anumber of reference targets of known design points on a large part. Inthis case, the large part is assumed to have been built identically to adefined design. This technique allows the laser tracker to “buck” intothe part's coordinate system, or to locate precisely the coordinatesystem of the tracker with respect to the coordinate system of the part.When a smaller part is to be mounted onto a larger part, a laser trackerwith a visible beam points onto the larger part and can thus designatethe mounting position to guide the mechanic in the assembly.

However, this technique only gives one point indicating the location ofthe part. Typical laser trackers are not able to directly measure thecoordinates of the mounted hardware relative to the reference targets orother mounted hardware. This is because typical laser trackers onlymeasure off retro-reflective targets, and because the line-of-sight pathbetween the laser and the retro-reflective targets is blocked.

Use of retro-reflective targets introduces additional time and laborcosts into manufacturing operations. Most retro-reflectors must bepositioned within a small range of angles to be useful, so time andeffort are expended setting up the targets. Further, theretro-reflectors must be periodically pointed and re-pointed to remainwithin the useful range of angles. Because of their angle-sensitivityand time requirements, retro-reflectors are not able to be used to makemeasurements in a production line as part of the production process.Instead, retro-reflectors are typically set up and measurements aretypically performed on back shifts, such as a midnight shift, whenproduction operations are not being performed.

Further, laser trackers cannot provide the factory aid functiondescribed above, such as would provide information about how the partshould be oriented. If information regarding orientation of the part isdesired, then the desired orientation information is currently providedby a different system using a different laser that passes through alaser galvanometer scanner that is positioned next to the laser tracker.The scanner motor and mirrors are much more agile than those of thelaser tracker, such that a pattern may be drawn at an update rate thatappears to be a projected pattern.

To project the pattern, the projector needs to know the part definitionand the position of the tool and/or workpiece onto which it projects thepattern. The laser radar allows the projector to acquire the position ofthe tool and/or workpiece. Because known systems use a separate trackerand a separate projector, the relative positions of the tracker and theprojector need to be known and resolved, especially when operating attolerances on the order of 1/1000 inch or less for critical operations.

It would be desirable to perform measurements without retro-reflectorsand project information using a single system. However, there is anunmet need in the art for a system and method for performingmeasurements without retro-reflectors and for projecting informationwith the same system.

SUMMARY OF THE INVENTION

Embodiments of the present invention provide a system and method fortargetless optical measurement and optical information projection.According to the present invention, one system is used instead of twoseparate systems for measuring and for projecting information. As aresult, position of one system does not have to be calibrated relativeto the other system. This can eliminate a major source of error inconventional systems between initial measurement of a part and relativepositioning of projection of a pattern or information. This can alsoreduce cost of the system because elements are shared betweenmeasurement and projection functions.

Also, measurements can be made without use of retro-reflectors. As aresult, embodiments of the present invention advantageously may be usedto make measurements and project information on-line as part of theproduction process. This can cut flow time for assembly while enhancingaccuracy and reducing undesired rework.

According to embodiments of the invention, systems and methods areprovided for targetless optical measurement and optical informationprojection. A non-contact optical measurement device is provided fordetermining at least one of position and orientation of a workpiece. Aprojector is provided for projecting a part definition on the workpiece.Advantageously, beams from the non-contact optical measurement deviceand the projector pass through common optics.

According to another embodiment of the present invention, a system isprovided for targetless optical measurement and optical informationprojection. A first non-time-of-flight laser is configured to project afirst laser beam onto a surface of a part under measurement. A rangemeasurement component is configured to receive reflection from the firstlaser reflecting off the surface of the part under measurement, and therange measurement component is arranged to determine range andorientation of the surface of the part under measurement relative to thefirst laser. A second laser is configured to project a second laser beamonto the surface of the part under measurement. The second laser beamhas a wavelength within the visible light spectrum, and the second laserbeam is co-aligned with the first laser beam. A scanning apparatus isconfigured to direct the second laser beam over the surface of the partunder measurement in a pattern of visible light.

According to an aspect of the present invention, the first laser beammay be an infrared laser beam. In this case, the first laser and therange measurement component may be provided as a laser radar. Ifdesired, the laser radar may be a chirped synthetic wave radar.

According to another aspect of the present invention, the first laserbeam may have a wavelength within the visible light spectrum. In thiscase, the range measurement component may include a plurality of videocameras that are arranged to triangulate a spot that is defined by thefirst laser beam on the surface of the part under measurement.

According to another aspect of the present invention, the scanningapparatus may include first and second scanning mirrors that are drivenby first and second scanning galvanometers, respectively, having firstand second axes that are substantially perpendicular to each other. Inthis case, an envelope of the first and second laser beams scanned withthe first and second mirrors maps out an approximate right pyramid. Ifdesired, the scanning apparatus may further include a third mirror thatis driven by a third scanning motor that is integrated with an angleencoder, such as a precision angle encoder. The third mirror is orientedaround 45 degrees or so with respect to its rotation axis (that issubstantially perpendicular to the axis of rotation of the secondgalvanometer). The third mirror may be driven substantially 360 degreesabout the third axis. In this case, an envelope of the first and secondlaser beams scanned with the first, second, and third mirrors maps out acylindrical shell with an angular width of the right pyramid. Byincorporating commercial-off-the-shelf components, the scanningapparatus provides scanning capabilities of a gimbal at a fraction ofthe cost.

BRIEF DESCRIPTION OF THE DRAWINGS

The preferred and alternative embodiments of the present invention aredescribed in detail below with reference to the following drawings.

FIGS. 1A, 1B, and 1C are high-level block diagrams of embodiments of thepresent invention;

FIG. 2 is a block diagram of optical components of the system of FIG.1B;

FIGS. 3A and 3B are perspective views of components of a scanningapparatus of the systems of FIGS. 1A-1C;

FIG. 4 is a top-level software block diagram of an embodiment of thepresent invention;

FIG. 5 is a functional block diagram of an exemplary geometricprojection algorithm;

FIG. 6 is a flow chart of an exemplary routine for an imagetriangulation algorithm; and

FIG. 7 is a block diagram of exemplary electronic and optoelectroniccomponents of the system of FIG. 1B.

DETAILED DESCRIPTION OF THE INVENTION

Embodiments of the present invention provide a system and method fortargetless optical measurement and optical information projection.According to the present invention, one system is used instead of twoseparate systems for measuring and for projecting information. As aresult, position of one system does not have to be calibrated relativeto the other system. This can eliminate a major source of error inconventional systems between initial measurement of a part and relativepositioning of projection of a pattern or information. This can alsoreduce cost of the system because elements are shared betweenmeasurement and projection functions. Also, measurements can be madewithout use of retro-reflectors. As a result, embodiments of the presentinvention advantageously may be used to make measurements and projectinformation on-line as part of the production process.

By way of overview and referring to FIG. 1A, an exemplary embodiment ofthe present invention provides a system 10 for targetless opticalmeasurement and optical information projection. A firstnon-time-of-flight laser 12 is configured to project a first laser beam14 onto a surface 16 of a part 18 under measurement. A range measurementcomponent 20 is configured to receive reflection 22 from the first laser12 reflecting off the surface 16, and the range measurement component 20is arranged to determine range and orientation of the surface 16relative to the first laser 12. A second laser 24 is configured toproject a second laser beam 26 onto the surface 16. The second laserbeam 26 has a wavelength within the visible light spectrum, and thesecond laser beam 26 is co-aligned with the first laser beam 14. Ascanning apparatus 28 is configured to direct the second laser beam 26over the surface 16 in a pattern 30 of visible light. A processor 32controls the first non-time-of-flight laser 12, the second laser 24, therange measurement component 20, and the scanning apparatus 28.

In one exemplary embodiment given by way of non-limiting example, thefirst laser beam 14 is an infrared laser beam. In another exemplaryembodiment, the first laser beam 14 may be a visible laser beam or anear-infrared laser beam. Exemplary implementations of opticalcomponents, the scanning apparatus 28, software components, andelectronic components will also be explained.

Referring now to FIG. 1B, in one embodiment of a system 10A the firstlaser beam 14 is a near-infrared laser beam. The laser 12 may be athermoelectrically cooled (TEC) laser, if desired. The first laser beam14 suitably has a wavelength within a range from around 880 nanometers(nm) to around 950 nm. However, the first laser beam 14 may have anywavelength as desired for a particular measurement application.

In one presently preferred embodiment, the first laser beam 14 has awavelength of around 880 nm. Advantageously, the firstnon-time-of-flight laser 12 may be provided (along with the rangemeasurement 20) as a laser radar, such as without limitation a chirpedsynthetic wave (CSW) laser radar. Advantageously, a CSW laser radar hasa signal-to-noise ratio that is high enough to measure coordinates of arandomly rough surface or feature (that is, a non-cooperative target).However, a CSW laser radar suitably may also be used to measurecoordinates of a cooperative target, such as a retro reflector. CSWlaser radars are known in the art. Given by way of non-limiting example,a suitable laser radar is described in U.S. Pat. No. 5,371,587, theentire contents of which are incorporated by reference. Details ofsignal processing for measuring range to the part 18 under measurementwith a CSW laser radar are set forth in concurrently-filed U.S. PatentApplication bearing attorney docket number BA1-03-1404 entitled“Ultra-Linear Signal Processing for Radar and Laser Radar”, the entirecontents of which are incorporated by reference.

In addition to a CSW laser radar, any suitable type ofnon-time-of-flight laser metrology device may be used as desired for aparticular measurement application. Given by way of non-limitingexample, suitable types of non-time-of-flight laser metrology devicesinclude, without limitation, laser radars based on frequency modulation,multi-tone frequency modulation, multi-tone amplitude modulation,coherent detection, and multi-wavelength frequency modulatedinterferometers, and the like.

Referring now to FIGS. 1A and 1B, when the range to the part 18 undermeasurement is measured by the first laser beam 14 that has a wavelengththat is within the infrared spectrum, optical information iscommunicated in the visible light spectrum by the second laser beam 26.The laser 24 may be a thermoelectrically cooled (TEC) laser, if desired.In one presently preferred embodiment, the second laser beam 26 suitablyis a green laser beam with a wavelength of around 532 nm. However, thesecond laser beam 26 may have any wavelength as desired within thevisible light spectrum. In this exemplary embodiment, the second laserbeam 26 is provided by the second laser 24 that is separate from thefirst non-time-of-flight laser 12. For example, the second laser 24suitably is a known laser, such as NVG, Inc.'s model SM635-5 laserdiode, operating at 635 nm, with 5 mW power. Such devices arecommercially available at various wavelengths between 635 nm to 670 nmfrom a variety of vendors.

Referring now to FIGS. 1A and 1C, in another embodiment of a system 10B,the first laser beam 14 may have a wavelength within the visible lightspectrum or within the near-infrared spectrum. In this case, the firstlaser beam 14 defines a spot 34 on the surface 16 of the part 18 undermeasurement. The near-infrared spectrum advantageously is invisible tothe human eye and does not interfere with the normal work environment.

The range measurement component 20 suitably includes a plurality ofvideo cameras 36 that are arranged to triangulate the spot 34 that isdefined by the first laser beam 14. However, if desired, the videocameras 36 may also triangulate on retro-reflective targets. The videocameras 36 suitably are digital cameras, such as charge-coupled device(CCD) digital cameras. By way of non-limiting example, a suitable CCDdigital camera includes without limitation a Kodak Megaplus CCD digitaloutput camera with 1320×1035 pixels and a maximum frame rate of around10 Hz. Such digital cameras operate in both the near-infrared spectrumand the visible light spectrum.

The second laser beam 26, operating within the visible light spectrum,is especially well-suited when the surface 16 of the part 18 undermeasurement is a randomly rough surface. Advantageously in this case,the first laser beam 14 and the second laser beam 26 may be generatedfrom the same laser. However, the first laser beam 14 and the secondlaser beam 26 may be generated by separate lasers, if desired.

Referring now to FIG. 2, the first non-time-of-flight laser 12 mayinclude lasers 12 a and 12 b. The lasers 12 a and 12 b may bethermoelectrically cooled (TEC) lasers, if desired. Outputs of thelasers 12 a and 12 b are optically coupled to input terminals 38 a and38 b of an optical splitter/combiner 40. Optical transport amongcomponents described herein for laser beam generation suitably isaccomplished with optical fibers.

An output terminal 42 a of the optical splitter/combiner 40 is coupledto provide optical signals for reference channels 44 a, 44 b, and 44 c.These reference channels are fixed reference lengths for absolutecalibration, which reference lengths are measured simultaneously witheach measurement of the distance to the part.

The output terminal 42 a is coupled to an input terminal 46 a of asplitter/combiner 48. An output terminal 50 a of the splitter/combiner48 routes the modulated laser light to the reference channel 44 a. Themodulated laser light is provided to an input terminal 52 a of asplitter/combiner 54 and an input of a photodiode 56 is provided to anoutput terminal 52 b of the splitter/combiner 54. An output terminal 58a of the splitter/combiner 54 is coupled to an optical fiber 60 that hasflat, polished fiber ends 62 and 64 that provide for partial reflection.The partial reflection defines the end points of the length of thereference channels, defined by the distance between the ends 62 and 64.The light from the partial reflection propagates back throughsplitter/combiner 54 to the input of the photodiode 56 through outputterminal 52 b where they interfere on photodiode 56. The electricalsignal generated by photodiode 56 carries the information to measure thereference length signal of channel 44 a.

An output terminal 50 b of the splitter/combiner 48 is coupled to aninput terminal 66 a of a splitter/combiner 68. An output terminal 70 aof the splitter/combiner 68 provides the modulated laser light to thereference channel 44 b, and an output terminal 70 b of thesplitter/combiner 68 provides the modulated laser light to the referencechannel 44 c. The reference channels 44 b and 44 c are constructedsimilar to the reference channel 44 a. For the sake of brevity, detailsof their construction need not be repeated for an understanding of thepresent invention.

An output terminal 42 b of the splitter/combiner 40 is coupled toprovide output of the first non-time-of-flight laser 12 to an inputterminal 72 a of a splitter/combiner 74. Output of the projection laser24 is provided to an input terminal 72 b of the splitter/combiner 74.The output of both of the lasers 12 and 24 is provided from an outputterminal 76 a of the splitter/combiner 74 as modulated laser light to aninput terminal 78 a of a splitter/combiner 80. Output ofsplitter/combiner 80, terminal 78 b, is provided to the input ofphotodiode 82. An output terminal 84 a is coupled to a flat, polishedend 86 of an optical fiber 88. The optical fiber 88 is coupled to anoutput telescope 90. Laser light from an object being measured iscombined with the light reflected from the flat polished end 86 androuted through combiner splitter 80 to photodiode 82 where theinterference between these two beams interferes, thereby generating anelectrical signal that encodes the distance to the object beingmeasured. Advantageously, the laser beams 14 and 26 are outputcollinearly—that is, co-aligned—from the output telescope 90 and areprovided to the scanning apparatus 28 (FIGS. 1A, 1B, and 1C). Thispermits the system 10 to be positioned without a need to calibrateposition of the laser beam 12 relative to position of the laser beam 24.This can eliminate a major source of error in conventional systemsbetween initial measurement of a part and relative positioning ofprojection of a pattern or information.

In a presently preferred embodiment, the scanning apparatus 28 is aprogrammable, rapid beam-steering (scanning) mechanism that directs avisible light beam, such as the laser beam 26, onto a surface, such asthe surface 16, with sufficient speed to act as a display of geometricpatterns and/or alphanumeric characters projected onto a part (withcorrect orientation and position on the part). However, the scanningapparatus is also preferably usable to direct the measurement laser beam14 onto the surface 16. In one presently preferred embodiment, thescanning apparatus 28 directs both of the laser beams 14 and 26 onto thepart 16. Advantageously, the scanning apparatus suitably is made fromreadily-available, commercial-off-the-shelf components, such as mirrors,motors, and encoders. By incorporating commercial-off-the-shelfcomponents, the scanning apparatus 28 provides scanning capabilities ofa gimbal at a fraction of the cost.

The components shown in FIG. 2 and described above are similar tooptoelectronic components shown and described in U.S. patent applicationbearing attorney docket number BA1-03-1404, the entire contents of whichare incorporated by reference. Further, embodiments of the presentinvention may use more than two lasers and/or more than three referencechannels as desired for a particular application.

Referring now to FIGS. 3A and 3B, in one embodiment the scanningapparatus 28 includes first and second scanning mirrors 100 and 102,respectively. The first and second mirrors 100 and 102 are driven byfirst and second scanning galvanometers, respectively, (not shown). Thefirst and second galvanometers have first and second axes a₁ and a₂ thatare substantially perpendicular to each other. The first and secondgalvanometers rotate the first and second mirrors 100 and 102 about theaxes a₁ and a₂, respectively, in directions shown by arrows 104 and 106,respectively. The mirrors 100 and 102 are rotated at a rate that isaround the same rate, and preferably no slower than, a refresh rate ofthe laser 24 that generates the pattern 30 to provide substantiallyflicker-free viewing of the projected pattern. A common refresh rate isaround 30 updates/sec. However, any refresh rate may be used as desiredfor a particular application. In this exemplary embodiment, an envelopeof the first and second laser beams 14 and 26 scanned with the first andsecond mirrors 100 and 102 maps out an approximate right pyramid.

If desired, the scanning apparatus 28 may further include a third mirror108 that is driven by a third scanning motor 110 having a third axis a₃that is substantially mutually perpendicular to the second axis a₂. Themotor 110 suitably is a rotary stage motor and associated encoder, eachwith a hollow center. The encoder suitably is a precision angle encoder.Advantageously, the laser beams 14 and 26 pass through the hollow centerof the motor and are permitted to optically communicate with the mirror108 without interference. The third mirror 108 may be drivensubstantially 360 degrees about the third axis a₃ in a direction asshown by an arrow 112. In this exemplary embodiment, an envelope of thefirst and second laser beams 14 and 26 scanned with the first, second,and third mirrors 110, 102, and 108, respectively, maps out acylindrical shell with an angular width α of the right pyramid. In oneexemplary embodiment given by way of non-limiting example, the angularwidth α of the right pyramid may be around ±20 degrees or so. However,any angular width α may be selected as desired for a particularapplication.

Referring now to FIG. 4, software 120 resides on the processor 32 (FIGS.1A-1C) and controls functions of the systems 10, 10B, and 10C (FIGS.1A-1C). A user interface 122, such as a graphical user interface, allowsa user to interact with the system and select functions and parametersas desired for a particular application. Measurement integrationsoftware 124 interfaces with the user interface 122 and controlsmeasurement functionality in response to selections communicated by theuser interface 122.

The measurement integration software 124 controls the followingmeasurement functionality: a geometric projection algorithm 126;scanning apparatus control 128; triangulation algorithms 130; imageacquisition algorithms 132; image processing algorithms 134; and a rangemeasurement engine 136. A brief description of each of thesefunctionalities will be set forth below.

Referring additionally to FIGS. 1A-1C and 5, the geometric projectionalgorithm 126 computes scan angles for the laser beam 26, therebypermitting the laser beam 26 to trace the pattern 30 on the surface 16regardless of contours, angles, roughness, or any irregularity of thesurface 16 other than direct line-of-sight obscuration. At a block 138,three-dimensional coordinates (in the system of coordinates of the part18) of the pattern 30, such as an alphanumeric character or the like,are calculated using projective geometry, and known part definition.

At a block 140, scanner-to-part transformation parameters are calculatedby performing an optimized best-fit of multiple points of surface 16previously measured by the system 10, 10A, or 10B, to thethree-dimensional design of surface 16, such as a computer aided design(CAD) model. The scanner-to-part transformation parameters permitthree-dimensional coordinates that define a location in the coordinatesystem of the part 18 to be converted to three-dimensional coordinatesthat define the location in the coordinate system of the system. At ablock 142, the three-dimensional coordinates from the block 138 aretransformed from the system of coordinates of the part 18 to the systemof coordinates of the system using the scanner-to-part transformationparameters from the block 140.

At a block 144, scanner calibration parameters are input from acalibration file provided by the vendor of the scanner apparatus 28 orby an off-line calibration process. These parameters include such thingsas the precise distance of mirror surfaces 100 and 102 to theirrespective axes a₁ and a₂, the precise angle between the normal vectorto mirror surfaces 100 and 102 to their respective axes a₁ and a₂, andthe precise distance and angle between axes a₁ and a₂. The scannercalibration parameters permit scan angles for the laser beam 26 to becalculated from three-dimensional coordinates in the coordinate systemof the system. At a block 146, the scanner calibration parameters fromthe block 144 are applied to the three dimensional coordinates from theblock 142, and scan angles for the laser beam 26 are computed. At ablock 148 the scan angles are output by the processor 32 to the scanningapparatus control software 128 (FIG. 4) as commands. The scanningapparatus control software 128 accepts single or multiple scan anglecommands and processes them to derive low level motion commands that itthen sends to the scanning apparatus 28. The scanning apparatus 28interprets these low level commands, which generates voltages andcurrents to drive the galvanometers to the appropriate scan angles, andreads the encoders to control the angles in a closed loop. The scanningapparatus 28 reports the encoder angles to the processor 32. Thefunctionality in the software 128 and the scanning apparatus 28 isstandard in commercially available galvanometer scanning systems such asthe Nutfield Technology Inc. model QuantumScan-30 galvanometer,SurfBoard USB Controller, and WaveRunner software products. Anadditional channel of control is implemented in one embodiment in whicha third mirror is added, and the additional angles are computed andcommanded in the same way.

The scanning apparatus control 128 controls all the axes of rotarymotion in the scanning apparatus 28. It is the set of software thataccepts angle commands, interprets them, and converts them to low leveldevice control commands. The Nutfield Technology, Inc. softwareWaveRunner is exemplary.

The triangulation algorithms 130 triangulate a centroid of the spot 34in the system 10B (FIG. 1C). The triangulation algorithms 130 performtriangulation calculations on signals provided by the video cameras 36.Using known triangulation techniques, the triangulation algorithms 130determine range and three-dimensional coordinates of the spot 34 in thecoordinate system of the system 10B.

Referring now to FIG. 6, in one embodiment an exemplary routine 131implements the triangulation algorithms 130. The routine 131 starts at ablock 133. At a block 135, two-dimensional coordinates (that is, acentroid) of the spot 34 (FIG. 1C) within a digital image acquired fromeach of the video cameras 36 (FIG. 1C) are computed. In one embodiment,by using background subtracted images a linearized mathematical model ofa tilted, elliptical, Gaussian spot is fitted to the edges of the targetimage. In another embodiment, an intensity-weighted-average technique isused to compute the centroid of the spot 34 (FIG. 1C). Fitting themathematical model of the spot to the edges of the target image isslower than the intensity-weighted-average technique but can be moreaccurate than the intensity-weighted-average technique. For example,fitting the mathematical model of the spot to the edges of the targetimage can be around four times slower than theintensity-weighted-average technique but can be up to twice as accuratethan the intensity-weighted-average technique. As a result, centroidscomputed by fitting the mathematical model of the spot to the edges ofthe target image are computed in image coordinates and can have atypical repeatability of approximately 1/200^(th) of a pixel.

At a block 137, the centroid is converted into two-dimensional solidangles. Focal length and distortion characteristics of lenses of thevideo cameras 36 (FIG. 1C) are used to remove lens distortion and toconvert the two-dimensional centroids into solid angle measurements—thatis, azimuth and elevation.

At a block 139, the two-dimensional solid angle measurements areconverted into three-dimensional rays. Position and orientation of thevideo cameras 36 (FIG. 1C) in three-dimensional space relative to anexternally-defined coordinate system of the system 10B are used toconvert the two-dimensional solid angle measurements intothree-dimensional rays. The three dimensional rays have origins at thecenter of the lens of the appropriate video camera 36 (FIG. 1C) andextend through the center of the spot 34 (FIG. 1C).

At a block 141, three-dimensional coordinates are computed from thethree-dimensional rays. The three-dimensional rays from the videocameras 36 (FIG. 1C) are combined to compute the three-dimensionalcoordinates that most closely intersect each ray. It will be noted thateach three-dimensional ray provides two constraints, or equations, whilethe three-dimensional coordinate has three unknowns. Thus, use of two(or more) of the video cameras 36 (FIG. 1C) gives rise to an overdetermined system of linear equations in three unknowns that can besolved using any one of several known algorithms, such as withoutlimitation Cholesky's method. The routine 131 ends at a block 143.

Referring back to FIG. 4, the image acquisition algorithms 132 controlthe cameras to acquire images simultaneously into one or more framegrabbers, which acquire and digitize the image data from the cameras,and provide the data in a file or memory available to the processor.This functionality is well known in the art and is available fromnumerous vendors who supply frame grabbers, such as National Instrument,Inc model NI-IMAQ software that controls a variety of NationalInstruments, Inc image acquisition boards, such as the model NI-PXI-1428Image Acquisition product.

The image processing algorithms 134 manipulate digital image data tocorrect for lens distortion, extract image features relevant formetrology, and provide output to the geometric analysis algorithms.Non-limiting exemplary commercial algoreithms are available fromNational Instruments, Inc, in the product NI Vision Development Module.

The range measurement engine 136 determines range to the part 18 whenthe laser 12 and range measurement component 20 are provided as achirped synthetic wave radar, as shown in FIG. 1B. The range to the part18 is provided in terms of coordinates in the coordinate system of thesystem. Details regarding the range measurement engine 136 are set forthin co-pending U.S. patent application bearing attorney docket number03-1404, the contents of which are incorporated by reference.

Referring now to FIGS. 1A, 1B, 2, and 7, exemplary electronic componentswill be explained. Control voltages are supplied from a fieldprogrammable gate array (FPGA) 200, such as without limitation aXilinx,Inc. model Vortex Pro II 2VP20 chip. A power driver 201, such asa high-speed metal-oxide-silicon (MOSFET) driver like a model IXDD402available from the Ixys Corporation, receives the control voltages andsupplies electrical power to the lasers 12 and 24. The lasers 12 and 24may be cooled by thermoelectric coolers (TECs) 203.

The range measurement component 20 includes photodiodes 202. Each of thephotodiodes 202 receives reflections of the laser beam 14 from thesurface 16 and outputs a signal that has an amplitude proportional tointensity of the received reflection. While three of the photodiodes 202are shown in FIG. 7, any number of the photodiodes 202 may be used asdesired. Suitable photodiodes may include, by way of non-limitingexample, a model EDR 512DRFC2 available from JDS Uniphase.

The signal from the photodiode 202 is input to an amplifier 204. Theamplified signal from the amplifier 204 is input to a digitizer (notshown) on the FPGA 200. The digitized signal from the FPGA is processedby the range measurement engine 136 (FIG. 4) to determine range to thesurface 18 and to generate three-dimensional coordinates in thecoordinate system of the system.

While the preferred embodiment of the invention has been illustrated anddescribed, as noted above, many changes can be made without departingfrom the spirit and scope of the invention. Accordingly, the scope ofthe invention is not limited by the disclosure of the preferredembodiment. Instead, the invention should be determined entirely byreference to the claims that follow.

1. A system comprising: a non-contact optical measurement device fordetermining at least one of position and orientation of a workpiece; aprojector for projecting a part definition on the workpiece; and commonoptics through which pass beams from the non-contact optical measurementdevice and the projector.
 2. The system of claim 1, wherein thenon-contact optical measurement device includes a first laser.
 3. Thesystem of claim 2, wherein the first laser includes a non-time-of-flightlaser.
 4. The system of claim 3, wherein the non-time-of-flight laserincludes a laser radar.
 5. The system of claim 4, wherein the laserradar includes a chirped synthetic wavelength laser.
 6. The system ofclaim 1, wherein the projector includes a second laser.
 7. The system ofclaim 6, wherein the second laser generates one of a visible laser beamand a near-infrared laser beam.
 8. A method comprising: determining atleast one of position and orientation of a workpiece with a non-contactoptical measurement device; projecting a part definition on theworkpiece with a projector; and passing beams from the non-contactoptical measurement device and the projector through common optics. 9.The method of claim 8, wherein determining at least one of position andorientation of a workpiece includes generating a first laser beam. 10.(canceled)
 11. (canceled)
 12. (canceled)
 13. The method of claim 8,wherein projecting a part definition includes generating a second laserbeam.
 14. (canceled)
 15. A system comprising: a first laser configuredto project a first laser beam onto a surface of a part undermeasurement, the first laser being a non-time-of-flight laser; a rangemeasurement component configured to receive reflection from the firstlaser reflecting off the surface of the part under measurement, therange measurement component being arranged to determine range andorientation of the surface of the part under measurement relative to thefirst laser; a second laser configured to project a second laser beamonto the surface of the part under measurement, the second laser beamhaving a wavelength within the visible light spectrum, the second laserbeam being co-aligned with the first laser beam; and a scanningapparatus configured to direct the first and second laser beams over thesurface of the part under measurement.
 16. The system of claim 15,further comprising a controller configured to control the first andsecond lasers, the range measurement component, and the scanningapparatus.
 17. The system of claim 15, wherein the first laser beamincludes an infrared laser beam.
 18. The system of claim 17, wherein thefirst laser and the range measurement component comprise anon-time-of-flight laser radar.
 19. The system of claim 18, wherein thelaser radar includes a chirped synthetic wavelength laser radar.
 20. Thesystem of claim 15, wherein the first laser beam has a wavelength withinone of the visible light spectrum and the near-infrared spectrum. 21.The system of claim 20, wherein the range measurement component includesa plurality of video cameras arranged to triangulate a spot defined bythe first laser beam on the surface of the part under measurement. 22.The system of claim 15, wherein the scanning apparatus includes firstand second scanning mirrors driven by first and second scanninggalvanometers, respectively, having first and second axes that aresubstantially perpendicular to each other.
 23. The system of claim 22,wherein the scanning apparatus further includes a third mirror driven bya third scanning motor integrated with an angle encoder, the thirdmirror being oriented around 45 degrees with respect to its rotationaxis, a rotation axis of the third mirror being substantiallyperpendicular to the axis of rotation of the second galvanometer. 24.The system of claim 23, wherein the third mirror is driven substantially360 degrees about the third axis.
 25. (canceled)
 26. (canceled) 27.(canceled)
 28. (canceled)
 29. (canceled)
 30. (canceled)
 31. (canceled)32. (canceled)
 33. A scanning apparatus for directing at least one laserbeam onto a surface of a part, the scanning apparatus comprising: firstand second scanning mirrors driven by first and second scanninggalvanometers, respectively, having first and second axes that aresubstantially perpendicular to each other; and a third mirror driven bya third scanning motor integrated with an angle encoder, the thirdmirror being oriented around 45 degrees with respect to its rotationaxis, a rotation axis of the third mirror being substantiallyperpendicular to the axis of rotation of the second galvanometer. 34.The scanning apparatus of claim 33, wherein the third mirror is drivensubstantially 360 degrees about the third axis.
 35. (canceled) 36.(canceled)
 37. (canceled)
 38. (canceled)
 39. (canceled)
 40. (canceled)41. A method of controlling projection of a pattern of visible lightonto a surface, the method comprising: inputting first three-dimensionalcoordinates of a location on a surface upon which a pattern is to beprojected; transforming the first three-dimensional coordinates tosecond three-dimensional coordinates; and computing scan angles fordirecting a beam of visible light in the pattern to be projected on thelocation on the surface.
 42. The method of claim 41, wherein the firstthree-dimensional coordinates are referenced to an object upon which thesurface is located.
 43. The method of claim 41, wherein the secondthree-dimensional coordinates are referenced to a system that projectsthe visible light onto the surface.
 44. A computer software programproduct for controlling projection of a pattern of visible light onto asurface, the method comprising: first computer software program codemeans for inputting first three-dimensional coordinates of a location ona surface upon which a pattern is to be projected; second computersoftware program code means for transforming the first three-dimensionalcoordinates to second three-dimensional coordinates; and third computersoftware program code means for computing scan angles for directing abeam of visible light in the pattern to be projected on the location onthe surface.
 45. The computer software program product of claim 44,wherein the first three-dimensional coordinates are referenced to anobject upon which the surface is located.
 46. The computer softwareprogram product of claim 44, wherein the second three-dimensionalcoordinates are referenced to a system that projects the visible lightonto the surface.